Constant speed telephone dial return mechanism

ABSTRACT

Mechanism for progressively balancing the unwinding spring tension of a telephone dial so as to effect a constant dialreturn speed and hence obtain a constant output pulse rate ratio from the telephone. An inner tubular cam face of spiral, repetitive wave form is swept by a brake consisting of a resiliently radially-outwardly-urged friction pin carried by the shaft of the dialing disk. An axially-directed drive pin also carried by the shaft is spring-urged to be (during dial return only) in driving relation with a unidirectionally rotatable toothed wheel which is jointly rotatable with a pulse wheel. Arrangement eliminates present spur gear, worm drive, and centrifugal regulator.

[ 51 Apr. 25, 1972 [54] CONSTANT SPEED TELEPHONE DIAL RETURN MECHANISM[72] Inventor: Werner Poppendieck, Reinerzstrasse 16, 1

Berlin 33, Germany [22] Filed: Feb. 16, 1970 [21] Appl. No.: 11,440

[30] Foreign Application Priority Data Feb. 14, 1969 Germany ..P 19 07544.6

[52] U.S.Cl. ..l79/90R FOREIGN PATENTS OR APPLICATIONS 867,122 11/1958Great Britain ..l79/9O R Primary ExaminerKathleen H. Claffy AssistantExaminer-Tom DAmico Attorney-Howard L. Johnson ABSTRACT Mechanism forprogressively balancing the unwinding spring tension of a telephone dialso as to effect a constant dialreturn speed and hence obtain a constantoutput pulse rate ratio from the telephone. An inner tubular cam face ofspiral, repetitive wave form is swept by a brake consisting of aresiliently radially-outwardly-urged friction pin carried by the shaftof the dialing disk. An axially-directed drive pin also carried by theshaft is spring-urged to be (during dial return only) in drivingrelation with a unidirectionally rotatable toothed wheel which isjointly rotatable with a pulse wheel. Arrangement eliminates presentspur gear, worm drive, and centrifugal regulator.

4 Claims, 5 Drawing Figures PATENTED APR 2 5 1972 SHEET 10F 2PATENTEnAPRzs r972 659 O57 SHEET 2 BF 2 FIG. 5

CONSTANT SPEED TELEPHONE DIAL RETURN MECHANISM This invention relates toan arrangement for progressively braking and uniformly regulating thereturn speed of signaling dials of dial telephones, thereby obtaining aconstant-rate output signal.

Almost without exception, the known mechanisms of this kind usecentrifugal regulators. These make it necessary for the assembly totransform the relatively slow dial-return speed to rapid motion. Only inthis way can a dial return of about one second at a pulse rate of 60 to40 ms and a total pulse of 100 ms be insured. The incorporatedtransmission elements consist in principle of a spur gear and worm drivelocated between the main shaft of the dialing disk and the centrifugalregulator; the shaft of the centrifugal regulator is thus parallel withthe hole plate.

A spur gear and worm drive as well as the centrifugal regulator greatlyincrease the cost of the assembly. Therefore this invention is directedto eliminating the spur gear and worm drive and avoiding the centrifugalregulator. As noted in the preceding abstract, all these parts may bereplaced by simpler components which consist of a spring-tensioned orresilient friction pin sliding on the particularly configured, innertubular face of a cam ring; this results in a substantial simplificationof the conventional dial sub-assembly.

The present solution to the problem is based on the observation that theforce stored in the drive spring by winding or turning the dial, whichforce decreases uniformly to zero upon complete return of the dial torest position and which force also uniformly decelerates the dialreturn, may be counterbalanced to produce an approximately uniformprogression by use of a resilient friction pin carried by the dial. Theresilient spring force of the pin-spring itself is also variable andthis is applied in inverse proportion to the force of the unwindingdrive spring, such brake force being produced by contact of the frictionpin with the radially varying face of the cam ring so as to provide aconstant dial return speed and thus to assure a constant pulse rate.

A presently preferred embodiment of the invention is illustrated by wayof example in the accompanying drawings wherein FIG. 1 is an elevationalview of the dial face of the unit.

FIG. 2 is a side elevational view thereof.

FIG. 3 is a transverse sectional view taken through the unit of FIG. 2along the line 33.

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 2.

FIG. 5 is an enlarged axial sectional view with portions in elevation.

A fixed numeral-carrying plate 12 is spacedly overlaid by a rotarydialing disk 13 having the usual circle of finger apertures spaced abovethe sequence of numerals on the plate 12 in the customary manner, theplate and disk being connected by a return spring 5. The dialing disk issecured to a central shaft 2 by a headed bolt 14, the shaft beingapproximately coaxial with a tubular housing 11 which traverses theplate 12. Distally the shaft 2 is fixed to a lateral housing arm 15which carries brake means in the form of a radially reciprocablefriction pin 9 which is urged outward by a helical spring 4 so as toposition the outer end of the pin in sliding registration with theradially-varying inner face of a cam ring 3. The latter is fixed to asupport 16 and as seen in FIG. 4, its inner contact face takes the formof a wavy, parabolic spiral whose radium increases in the returndirection of the dial 13. When the telephone user is dialing (clockwisein FIG. 1), the brake force of the cam ring 3 progressively increases,and at the same time spring tension is accumulated in the dial returnspring 5. When the user then releases the dial 13, the result is a veryuniform or constant unwinding or return of the dialing disk 13 due tothe balancing of the spring tension of 5 and the brake pressure of thefriction pin on the cam face 3.

Still more distal from the dial face is a sprocket wheel or toothedannulus 7 and a peripherally-lug-projecting wheel 10 axially spacedapart and fixedly connected to ether by a tubular shaft 17 which isgenerally coaxial with t e upper shaft 2.

The members 7, 10, 17 are jointly rotated by an axiallydirected drivepin 8 during return of the dialing disk 13, the pin being reciprocablyhoused in a socket 18 of a diametric extension 19 of the radial arm 15,such rotation thus actuating the pulse transmitter l. The drive pin 8 ismaintained in contact with the toothed rim of the sprocket wheel 7 by acoil spring 20. It will be seen that the parabolic wave form of the camface 3 corresponds to the uneven load through the pulse transmitterresulting from return movement of the dial following the traversing eachpulse intermission during which the pulse transmission is not actuatedby the wheel 10. Thus the unwinding wave pattern for the friction pin 9produces an approximately uniform decrease of the frictional brakingforce. The advantages of such simplified construction over that of theprior art should be apparent.

I claim:

1. in combination with a pulse-activating dial telephone having aspring-restrained rotary dialing disk normally returnable to restposition by release of spring tension which has been accumulated by dialrotation, the improvement comprising a counterbalancing second tensionmeans operative in response to return rotation of said dialing disk andadapted progressively to brake said released spring tension in inverseproportion to its decreasing force so as to effect a constant dial-retumspeed and thereby assure a constant output pulse rate from thetelephone, said second tension means including radially-varying cam ringmeans and substantially radially directed brake means disposed tofrictionally follow the radially-varying curvature of the cam ringmeans, one of the pair of cam ring means and brake means being carriedby the rotary dialing disk.

2. The combination of the preceding claim 1 wherein said cam ring meanscomprises a cam face of substantially spiral form and said brake meanscomprises a substantially radially tensioned friction pin carried by arotary shaft of said dialing disk and resiliently retained in slidingcontact with the spiral face of said cam ring means.

3. The combination of the preceding claim 2 wherein said spiral cam faceis characterized by a repetitive wave pattern and the radius of saidspiral increases in the direction of dial return.

4. The combination of the preceding claim 2 which additionally includespulse transmitting connecting means com prising a unidirectionablyrotatable toothed annulus and a drive member connected to said rotaryshaft and functionally retained in drive relation with said annulus onlyduring return movement of said dialing disk.

a a a a UNITED STATES PATENT OFFICE QER'HFECATE 0F CGRECTWN Patent No.3, 659 O57 Dated April 25 1972 Invent' (s) Werner Poppendieck It iscertified that error appears in the above-identified patent and thatsaid Letters Patentare hereby corrected as shown below:

Column 2, line 2, radium" shoulfi read radius lines 23-24, cancel"following the" Signed and sealed this 12th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM P0-10 0 (10-69) USCOMM-DC cows-P59 US. GOVERNMENTPRINTING OFFICE [9G9 0-366-385.

1. In combination with a pulse-activating dial telephone having aspring-restrained rotary dialing disk normally returnable to restposition by release of spring tension which has been accumulated by dialrotation, the improvement comprising a counterbalancing second tensionmeans operative in response to return rotation of said dialing disk andadapted progressively to brake said released spring tension in inverseproportion to its decreasing force so as to effect a constantdial-return speed and thereby assure a constant output pulse rate fromthe telephone, said second tension means including radially-varying camring means and substantially radially directed brake means disposed tofrictionally follow the radially-varying curvature of the cam ringmeans, one of the pair of cam ring means and brake means being carriedby the rotary dialing disk.
 2. The combination of the preceding claim 1wherein said cam ring means comprises a cam face of substantially spiralform and said brake means comprises a substantially radially tensionedfriction pin carried by a rotary shaft of said dialing disk andresiliently retained in sliding contact with the spiral face of said camring means.
 3. The combination of the preceding claim 2 wherein saidspiral cam face is characterized by a repetitive wave pattern and theradius of said spiral increases in the direction of dial return.
 4. Thecombination of the preceding claim 2 which additionally includes pulsetransmitting connecting means comprising a unidirectionably rotatabletoothed annulus and a drive member connected to said rotary shaft andfunctionally retained in drive relation with said annulus only duringreturn movement of said dialing disk.